Field of the Invention
The present invention relates to an exposure apparatus for exposing a substrate through an original (mask) and a device manufacturing method using the exposure apparatus.
Description of the Related Art
A substrate stage (also referred to as a wafer stage) provided in a semiconductor exposure apparatus (stepper, scanner) vibrates after being driven, though only slightly. However rigid the substrate stage may be, it always vibrates upon receiving a force. Under the recent circumstances where accuracy on the order of nanometers is required, the influence of the slight vibration of the substrate stage on the exposure accuracy cannot be neglected.
To reduce the influence of the vibration of the substrate stage on the exposure accuracy, the exposure apparatus includes a measurement device for measuring the vibration of the substrate stage, in addition to the substrate stage. Widely employed is an exposure method in which the substrate stage is driven, the controller of the exposure apparatus confirms using the measurement device that the vibration has so converged not to affect the exposure accuracy, and then, the exposure process, that is, exposure light irradiation is started. In this case, after confirming that the vibration has converged to some extent or has a tendency to converge, the exposure process is started. For this reason, the influence of the vibration on the exposure accuracy is greatly reduced.
Not only a high accuracy and advanced microfabrication but also shortening the time of the exposure process of a substrate is required for the exposure apparatus. The count of reticle (mask) transfer to one substrate may be 100 at maximum, although it changes depending on the application purpose of the substrate. For this reason, it is necessary to shorten the time from the start of substrate stage driving till the start of the exposure process, that is, exposure light irradiation.
To shorten the time from the driving of the substrate stage to the start of the exposure process, Japanese Patent Laid-Open No. 9-134864 discloses a technique of starting exposure by predicting the time at which the vibration would converge, instead of using the convergence of the vibration of the substrate stage as a trigger to start the exposure process. The technique disclosed in Japanese Patent Laid-Open No. 9-134864 can eliminate the process (time) of confirming the convergence of the vibration and move forward the process (time) of causing the controller to issue an exposure start command as compared to the prior art. It is therefore possible to shorten the time from the driving of the substrate stage till the start of the exposure process.